CA2479708A1

CA2479708A1 - Pipe joint

Info

Publication number: CA2479708A1
Application number: CA002479708A
Authority: CA
Inventors: Kazuhiko Sugiyama; Keiko Hada; Eiji Ideta; Nobukazu Ikeda; Naofumi Yasumoto; Michio Yamaji
Original assignee: Individual
Current assignee: Fujikin Inc
Priority date: 2002-03-20
Filing date: 2003-03-19
Publication date: 2003-09-25
Also published as: IL164121A0; CN1643289A; TWI289642B; IL164121A; KR100981082B1; EP1486715B1; EP1486715A1; WO2003078884A1; KR20040093162A; JP3538737B2; DE60319352T2; US7497482B2; CN100390455C; TW200306395A; US20050179259A1; DE60319352D1; EP1486715A4; AU2003221426A1; JP2004053006A

Abstract

An annular recess portion (7) is provided in an end face of a synthetic resi n- made first joint member (2) and an annular projection portion (8) is provide d on an end face of a synthetic resin-made second joint member (3). The projection portion (8) is fitted into an opening portion of the recess porti on (7) into which a synthetic resin-made gasket (4) is fitted. When a pipe joint(1) is tightened adequately, the inner face of the recess portion (7) o f the first joint member (2) and the outer face of the projection portion (8) of the second joint member (3) are in close contact with each other over substantially the entire surface through the gasket (4), a portion (2d) located radially inside the recess portion in the end face of the first join t member (2) and a portion (3d) located radially inside the projection portion on the end face of the second joint member (3) are in close contact with eac h other over substantially the entire surface area, and a portion (2e) located radially outside the recess portion in the end face of the first joint membe r (2) and a portion (3e) located radially outside the projection portion on th e end face of the second joint member (3) are also in contact with each other over substantially the entire surface area.

Description

SPECIFICATION
PIPE JOzNT
TECHNICAL FIELD
The present ~.nventian ralatae to pipe joints, and mQra partiaula~rly to a pipe point comprising ,joint members made of synthetic rosin and joins~d to aeoh other by acrev~r means.
BACKGROUND ART
aansrally used in fluid control devices, !ox exempla, far manufacturing gemiconduotors nre pipe joints which comprise a pair of tubular joint members, an annular gasket interposed batwe~sn the abutting end faces of the two jpint members and acssw mex~ns for joining the two ,jpint members. With such pip~ joints, the tubular ,joint members and the gaskest are usually made of c~ metal, such as SUS~16L or l:Lko stainless steel.
Whiles various fluids are passed through conventional pipe joints of stainless steel in the prc~ceas for manufac-tuning semiaonduatcara, 'these fluids include those having propsrtie~$ to readily corrode metals, auah as acidic ammonium fluoride, and it ia'desired to improve the point.
Although it appears fee~sible to make the members of the pipe joint from 1~FA or like synthetic resin, synthetic resin members undergo a greater alteration in shape (e. g.
stress relaxation Qr cold flow) With time thr~rr metal members, and the sp~o~,fia pressure occurring between the member8 at the abutting poz~tions gradually decreases, possibly resulting in leakage of the fluid.
An object of the present invention is to pro~tride a pipe joint wherein the portions to be brought into contact ' W~.th a f7.uid are made of a synthetic resin and which z~~tains ability to prevent fluid larks despite the lapse of time.
DI6CLpSURE OF' THE INVBNTTON
The present invention provide$ ae a first feature thereof a pipo joint comprising a fir$t and ti second tubular joint member of synthetic resin, o synthetic resin gasket interposed between abutting portions of the ,joint mernbera and screw means for joining the ,joint members, the pipe joint being characterized in that the first joint member is provid~d ire an abutting end face thereof with nn annular recessed portion having an Qpening remaining therein with the gasket entirely fitted th~rein, the seaQnd point member being pxovided with an annular ridge on an abutting end face thereof, the ridge being fitted in the opening of the recessed portion with the gasket fitted in the reoesaed portion, an outer surface of the r~.dQe of the second ,point member being pre$s~d against an inner surface of the reca~ssed portion off' the first joint member with the gasket interposed between the surfaces in intimate contact therewith approximately over the entire surface ar~ss whan the pipe point is proper~,y tightened up, a portion of the abutting es~d face of the first point member positioned xsdiallp inwardly of the recessed portion being then in intim~rte contact with a portion of the abutting end face of the second point member positioned radially irrr~erdly of the ridge approximatelx . over the entire surfaoe areas thereof, a poz-tion of the abutting end face of the first point member positioned radi~xliy outwardly of the recseased portion being then in intimate contact with a portion of ~thg abutting end face of tha $ocond point member positioned radially outwardly of the ridge approxim~etely oven the entire surface areas thereof.
The present invention provides as a second feature 20, thereof a pipe point compri~sirig a first and a ~recond tubular point member of synthetic resin, and screw means far joining the ,point memb~rs, the pipo point ba.ing characterized in that the first 3oint member irs provided with an annular recas$ed portion in an abutt:Lng end face thereof, the second point member bgir~g provided with an annular ridge on an abutting cnd face thereof, the ridge of the second joint mQmber being fitted in the recessed portion of the first joint member, with an out~r surface of the ridge in intimate contact with an inner surface of the recessed portion approximately over the entire surface areas when the pipe joint is properly tightened up, a portion of the abutting end faoe Qf the first joint member positioned radially inwardly of the recessed portion being than in intimate contact with a portion of the abutting end face of the second joint member positioned radially inwardly of the ridge approximately over the entire surface areas thereof, a portion of the abutting end fac~
of the first joint member positioned radially outwardly of the recessed portion being then in intimate contact with a i5. portion of th$ abutting end faoe of the second joint member positioned radiaily outwardly of the ridge .
approximat~ly oves the entire surface areas thereof.
With the pips joint according to the second feature of the invention, the ridge of the second joint member may comprise a portion formed integrally with the Second joint member and a portion formed separately from the integral portion, the portion integral with the ridge of the fir$t . aoint member being in intimate contact with the separate portion of the second joint Member When the pipe joint is properly tightened up, The present invention provides as a third feature . thereof a pipe joint comprising a first dnd a second tubular joint member of synthetic resin, a synthetic rQSin gasket interposed between abutting portions of the joint 5 members and screw m~ans for joining the point members, the pipe joint being characterized in that each of the joint members is provided in an abutting end face thereof with an annular recessed portion for forming a portion for accommodating the gasket therein when the joint members 10. are butted against each other, the gasktt being in intimate contact with an inner surface of the recessed portion of the first joint member approximat~ly over the entire area thereof when the pipe joint is properly tightened up, a surfaoe portion of the gasket exposed from the same recessed portion being then in intimate contact with an inner surface of the recessed portion of the second joint membex approximately over the entire area thereof, a portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof being then in intimate contact With a poxtion of th~ abutting and face of the second joint member positioned radially inwardly of the recessed portion thereof approximately over the entire surface areas thereof, a portion of 'the abutting ~nd Ease of the first point member positioned radially outwardly of the recessed portion thereof being then in intimate contact with a portion of the abuttxn9 and face of the second joint member positioned radially outwardly of the reaessad portion thereof approximately over the entire surface 5, erase th~reof.
The first to third features of the invention provide pipe ~ointa having sustained ability to prevent leaks of fluids despite the lap:e of time although the poxtions thereof to be exposed to the fluid are made of synthetic r~sin. Tha pipe joint embodying the second feature of the invention further has the advant$ge of being reduced in the number of components, while the pipe joint according to the third features of the invention has the advantage that the gasket is easily removable in disassembling the pipe joint.
The pips joint according to the third feature of the inv0ntion may be so d~signed that the portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof axially projects beyond the radially outward portion thereof, and . that the portion of the abutting and face of the second point member positioned radiaily inwardly of the recessed portion thereof also axially projaats beyond the radially outward portion thereof. Thi portion of the shutting end face of the first joint member positioned radially inwardly of the recessed portion thereof may be flush with the bottom surface of the reoesaed portion thereof, the radially outward portion of the first joint member axially pro~eating beyond the bottom surface of the recessed portion thereof, the portion of the abutting end face o~
the second point member radially inward of the reaeesed portion thereof axially pro~eoting beyond the bottom surface of the recesee~ portion thereof, the radially outward portion of the second joint.mgmber being ssially reaegsed from the bottom surface of the recessed portion thereof. Furthermore, the portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof may be recessed from the bottom surface of the recessed portion thereof, the radially outward portion of the fir:t point member axially prd~ecting beyond the bottom surface Qf the recessed portion they~of, the portion of the abutting arid face of the second joint member radially inward of the recessed portion thereof axially projecting beyond the bottom surface of the recessed portion thereof, the radially outward portion of the second joint msmbBr being axially recessed from the bottom surfaaa of the recessed portion thereof.
The pipe joint according;to each of the features of 25~ the invention is preferably so designed that when the pipe point is manually tightened up, n first Qap is present between the portion of the abutting end face of the first 3oint member positioned radially inwardly of the rcoessed portion thereof and the portion of thn abutting end face of the second point member positioned rndially inwardly of the ridge or the recessed portion thereof, s seoond gap garaater than the first gap being present between the portion of the abutting end face of the first point member positioned radially outwardly of the reoessad portion thereof and the portion of the abutting end face of the second faint member positioned radially outraardly of the ridge or the recessed portion thereof. When thu$
constructed, the pipe point has portions of grant spaaific pressure, portions of medium specific pressure and portion IS of small specific pressure. burins the first half of th~
period of use, a reduoed pressure occurs at the portions of great spocifio pressure, whereas the pressure drop is suppressed at the portions of medium specific pressure during this period. Thi$ enables the pipe ~o3nt to retain 20~ fluid leak preventing ability over a prolonged period of time.
The first gap is prdferabiy at laa8t 4.1 mm to not greater than 0.4 mm, morn preferably at least 0.15 mm to not greater than 0.3 mm. The second gap is preferably at 25 least 0.2 mm to not greater than O.fi mm, more preferably at least O.ZS mm to not greater than 0.5 mm. Tha difference between the second gap and the first gap is pref~rably at least O.QS mm to not grsater than 0.3 mm, more preferably at least 0.1 mm to not greater than 0.2 mm.
Zn the pips joint according to each of the features of the invention, each of the joint members may b~ provided at the abutting end face thereof with a flenQe portion, the screw means comprising an annular male screw member having a forward end face in bearing contact With the flange portion of one of the joint members, and a cap nut fitted around the other joint member and having a top wall in bearing contact with the flange portion of said other joint member, the cap nut being screwed on the male screw I5 member. The male screw member and the cap nut are held out of contact with the fluid flowing through the point members, may therefore be made of a metal or can of course be rnada of a synthetic resin. The flnnge gortiona of the joint members are preened axially inward by tightening up the sap nut on the male strew member, wh~rebx the two joint members are jainsd fluid-tightly.
In each of the pips joints aaeoxdiag to the feature$
' of the invention, at least one of a apace between the male screw member and the flange portion of said one joint member and a apace between th~ top wall of the cap nut and 1~
the flange portion of skid other flange member may have disposed therein a biasing member for biasing one of the point members toward the other point member. An annular clearance may be formed inside the cap nut around the flange portions of the ,joint members and may have an annular spacer diapo$ed therein, at ldast one of a space between the cap nut top wall and the spacer and a specs between the male screw member and the spacer having a biasing member provided therein for biasing one of the 14~ point members toward the other faint mwnber. 8ven if the ,joint members and the gasket which are made of synthetic reoin undergo an alteration (e_g_, stress relaxation or cold flow) with time, a spec3,fic pressure greatly influenoinQ the ability to prevent fluid leaks can then ba maintained to ensure more reliable fluid Leak preventing performance because one of th~ joint members is b~.ased toward the other point member at all times.
Preferably, a synth~tia resin thrust ring is interposed between they oap nut top wall and th~ flange portion of the faint member. As the cap nut is rotated for tightening up, the thrust rang then comes into sliding aoatact with the sap nut and the point member, preventing the cap nut and the ,joint member from rotating together.
xn this case, this thrust''ring may have an out$ids diameter larger than the inside diameter of the cap nut, with err annular recess formed in as inner periphery of the oap nut for acoommodatiag an outer peripheral edge of the thrust ring.
The thickness of the thrust ring is preferably equal to or smaller than the thickness of the gasket and is preferably as small a$ possible from the viewpoint of stress relaxation.
Examples of $ynthetia resins useful fox making the point members are fluorocarbon re8ins such as PFA.
Examples of synthetio resins useful for making the gasket are fluorocarbon resins suoh as PTFE. A1$o uaaful are othQr fluorocarbon resins, such as FEP, PCTFfi ~.nd ETFE, and other synthatiQ resins. The point members and the gasket may ba made from the same material. Tha synthetic resin for making the thrust ring is, far example, the same as the material for thg $askat, snd may b~ a resin smaller than the gasket material in coeffici~nt of sliding friotion (more smoothly slidable).
BRIEF DESCRIPTION QF THE DRAWINGS
2O' FIG. 1 is a view in longitudinal section showing a first embodiment of pipe ~oirit according to a first feature of the invention.
FIG. 2 inaludas gnlarged''fra~mantary views in longitudinal section of thg cams, (a) showing the point as ' 12 tightened up manually, (b) showing tho joint as tightened up properly.
F=G. 3 is a view in longitudinal Section showing an embodiment of pipe joint ~ccord3ng to n s~cond feature of the invention.
FrG. 4 is an enlarged fragmentary view in longitudinal section of the same.
F=G. 5 is n view in longitudinal section showing a first embodiment of pipe joint aooording to a third feature of the invention.
FIG. b ie a visw in longitudinal section showing a second embodiment of pipe joint aaoording to the third feature of the invention.
FIG. 7 is a view in lon~itud3nal section showing a third embodiment of pipe joint according to the third . feature of the inv~ntion.
FIG. 8 is a view in longitudinal nection showing another embodiment of pipe joint aocording to the first feature of the invention.
2Q FIG. 9 is a view 3n longitudinal section showing another embodiment of pipe joint according to the first fsature of the invention.
FIG. 10 is s view in longitudinal section showing another embodiment of pipe.jbint aaoording to the first feature of the invention.

FIG. 11 is a view in longitudinQl section showing another embodiment of pipe point according to the first feature of the inv~ntion.
HE$T MO'~.7E QF CARRYING OUT THE xNVENTION
Embodiments of the present invention will b~ described below with reference to the drawing .
FIG$. 1 and 2 show a pipe ,point embodying a first feature of the invant:Con. With reference to F=G. 1, the pips point 1 comprises a first tubular point member 2 of synthatio resin, a saaond tubula~e 3o.int member 3 of sxnthetio resin, a synthetic resin annular gssket 4 having a reatangul~xz~ cross $eotion end interposed between abutting portions of the two ,jofr~t members 2, 3, an annular m~.la screw member 5 fitted around the $acond point member 3, end a cap nut 6 fitted around the first ~vint member 2 and sare~wed on the male aarem member 5.
The ,point members 2, ~ are equal in inside diameter, aaoh have a predetermined inside diameter over the entire length, and comprise thick walk. portions Via, 3a closer to the abutting portions, thin gall portions 2b, 3b remote from the abutting portions and flange portions 2c, 3c formed at they abutting ends of,tha thick wall portions Via, 3a, respectively. '~ , 2~ha.firgt point member 2 has an annular reaeased portion 7 reatarigular in cross section and formed in a radially intermediate portion of the abutting end face thereof. The second joint member 3 has an annular ridge 8 rectangular in arose section and formed on n radially intermediate portion of the abutting end face thereof.
The male screw member 5 and the cap nut 6 are made of metal., A flange portion 5a in the form of a hexagonal prism is formed on the male screw member 5 at an end thereof opposite to the abutting portion. Th$ cap nut has a top wall 6a in the form of a bored di$k and formed at an end thereof opposite to the abutting portion. The male screw member 5 has an inside diameter approximately equal to the outside diameter of thick wall portion 3a of the second point member 3. The top wall 6a of the cap nut 6 has an inside diameter approximately equal to the outside diameter of thick wall portion 2a of the fir9t point member 2. As the cap nut 6 is tightened on the male screw member 5, the male screw member 5 pushes the flange portion 3a of the second joint memb~r 3 axially inward, while the cap nut 6 pushes the flange portion 2c of the first point member 2 axially inward, whereby the two point members 2, 3 are brought into intimate contact with each other, with the gasket 4 interposed therebetween.
The recessed portion 7 0~ the first joint member 2, the ridge 8 of the seoond joint member 3 and the gasket 4 are approximately equal in inside diameter. The recessed portion 7 0~ the first joint member 2, the ridge B of the second joint member 3 and the gasket 4 are also approximately equal in outside diameter. Tha depth of the recessed portion 7 is greater than the amount of projection of the ridge 8, and the thickness of the gasket 4 is smaller than the depth of the reagssed portion 7.
The depth of the recessed portion 7 is slightly smaller than the sum of the amount of projection of the ridge 8 and the thickness of the gasket 4.
FzG. 2(a) shows the cap nut 6 as manually tightened up on the male screw member 5, and FIQ. 2(b) shows the cap nut as further tighten~d up properly from this state using a wrench or the like.
when the pipe joint 1 is in th& manually tightened state, the gasket 4 is fitted in its entirety in the recessed portion 7 of the first joint member 2, with the ridge 8 of the second joint member 3 pre$sing the gasket 4 against thn bottom surface of the recessed portion 7, as shown in FIG. 2(a). A first gap ~1 is present between the portion zd of the abutting end fnae of the first joint member 2 which is positioned radially inwardly of the raaessed portion 7 and the portion 3d of the abutting end face of the ssaond joint mem$er 3 which is positioned radially inwardly of the ridge 8. A second gsp G2 greater than the first gap G1 i~ present between the portion 2s of the abutting end face of the first point member 2 which is positioned radially outw~rdiy of the recessed portion 7 and the portion 3e of the abutting $nd face of the aocond S point member 3 whioh is positioned radially outwardly of the ridge 8. Example9 of dimensions of these portions are as follvw$. Ths portion 2d radially inward of the recessed portion 7 of th$ first point member 2 is flush with the portion 2e radially outward thereof, the depth of the recessed portion 7 is 1.5 mm, the portion 3d radially inward of the ridge 8 of tho second point member 3 axially projects by 0.2 mm beyond the portion 3e radially outward thereof, thg amount of pro~sction of the ridge 8 is 0.8 mm based on the radially inwnrd portion 3d, the gnskat 4 is 1 mm zn thickness, the first gap G1 is 0.3 mm, and the second gap G2 is 0.5 mm.
With refsronce to F1G. 2(b) showing the pipe point Z
as properly tightonsd up, the gasket 4 and the ridge $ of the second point member 3 are entirely fitted in the recessed portion 7 of the first point member 2, thg outer surface of the ridge 8 of the member 3 is pressed against the inner surface of the recessed portion 7 of the member 2 with the gasket 4 interposed therabetwssn while holding intimate contact with one anther approximately over the entire opposed surfaces, the radially inward portion 2d of the first joint member abutting end face is in intimate contact with the radial inward portion 3d o~ the $scond joint member abutting sad face approximately over the entire opposed faces thereof, and the radial inward portion 2e of the first joint member abutting end face is also xn intimate contact with the radially inward portion 3e of the second joint member abutting end face approximately over the entire opposed ~aces~thereof.
FxGB. 3 and 4 $how a pipe joint embodying a second feature of th~ invention. With reference to FIG. 3, the pipe joint 11 comprises a first tubular joint member X2 of synthetic resin, a second tubular joint member 13 of synthetic r~s3n, an annular male screw member S fitted around the second joint member 13, and a cap nut 6 fitted 15. around the first joint member 12 and screwed on the male screw m~er S.
The joint members 12, 13 are squat in inside diem~ter, each have a predetermined inside diameter over the entire length, and comprise thick wall portions 12a, 13a closer to abutting portions, thin wall portions 12b, 13b remote from the abutting portions and fxange portions i2c, 13c form~d at the abutting ends of the thick wall portion$
12a, 13a, respectively.
Tha first joint member 1~ has an annular recessed portion 17 rectangular in cross section and formed in a radially intermadieta portion of the abutting and face . thereof_ The second joint member 13 has an annular ridge 18 reotangular in oroas section and formed on a radi811y intermediate portion of the abutting end face thereof.
Tha male sorew m~obar 5 and the cap nut 6 era made of metal. A flange portion 5a in the form of a hexagonal prism is formed on the male soraw member S at an end thereof opposite to the abutting portion. The cap nut has a top wall 6a in the form of a bored disk and formed at an 10, end thereof opposite to the abutting portion. The mal~
aorew member S has an inside diameter epproxim~tely equnl to the outside diameter of thick wall portion 13a of the second joint member 13. The top wall 6a of the oap nut 6 has an inside diameter approximately equal to the outside 1S diameter of thick wall portion 12a of the first joint member 12. As the cap nut 6 is tightened on the male aorew member 5, the male screw member 5 pushes the flange portion 13c of the second joint mevmber 13 axially inward, while the oap nut 6 pushes the flange portion 12C of the 20 first joint member 1Z axially inward, whereby the two joint members 12, Z3 era brought into intimate contact with each other with the ridge 18 fitting in the reoessed portion 17_ The recessed portion i7 df the first point member 12 25 and the ridge 18 of the second joint member 13 era sppxoximately equal in inside diameter. The r~ces~ed portion 17 of the first point member 12 and the ridge 18 of the second point rnembsr 13 are also approximately equal in outside di~smster. The depth of the r~oesa~d port3pn 17 5~ is smaller than the amount of projection of the ridge 18.
FIG_ 4 shows the cap nut 6 as manually tightened up on the male screw member 5. When the pipe point 11 i$ in the manually tighten~d State, tho ridge 18 of the second point member 13 is fitted in the recessed portion 17 of the first joint membex 12, with thgi outer end face of the ridge 18 pressing ageinst the bottom face of the recessed portion as shown in the drawing. A first gap Q1 is . present between the portion lad of the abutting end fees Qf the First point member i2 which is positioned xadially inwardly of the recessed portion 17 and the portion 13d of the abutting end face of the eeaond point member i3 which is positioned radiaZly inwardly of the ridge 18_ A second gap G2 greater than the first gap GI is present between the portion 12a of the abutting end pace of the first point mambex 12 which is positioned radially outwardly of the reoeased portion 17 and the portion 13e of the abutting end face of the second faint member 13 which is positioned radially outwardly of the ridge 18. examples of dimensions of these portions are as follows. The 2S portion 12d xadially inward of the recessed portion 17 of the first point member 12 is flush with the portion 12e radially outward thereof, the depth of the reoesaad portion 17 is 1.5 mrn, the portion 13d rsdially inward of the ridge 18 of the Second point member 13 is axially ,5 pro~acted by 0.2 mm beyond the radially outward portion 13e, the amount of projection of the ridge 18 is 1.8 mm based on the radially inward portion 13d, the first gap G1 is 0.3 mm, and the s~cond gap G2 is 0.5 mm.
When th~ pipe point il is properly tightened up as 10 further tighta~md from the state of FIO. 4, the ridge 1$
of the ascend point member 13 is entirely fitted in th~
reaQSSed portion 17 of the first point member 12, the out~r surface of the ridge 18 of the membex Z3 is in intimate contact with the inner surfaoe of the reoeesed Z5 portion 17 of the m~mber 12 approximately dvex the entire . arses of the surfaces, the portion 12d of the abutting end face of the first point rnembar 12 which is positioned radially inwardly of the recessed portion 17 is in intimato contact with the portion 13d of the 2~butting and 20 face of the second point member 13 which is positioned radially inwardly of the ridge 18 approximately over the entire opposed faces thereof, and the portion 12e of fibs abutting ~nd fave of the first point member 32 which 18 positioned radinlly outward of the recessed portion 17 is also in intimate oontact with the portion 13e of abutting ~l end face of the e~ecorrd joint member 13 which is positioned radially outward of the ridge 18 approximately over the . entire opposed faces thereof.
FIG. 5 shows a first embodiment of pips joint according to a third feature of the invention. with reference to FIG. 3, the pipe joint 21 comprises a first tubular point member 22 of synthetic resin, a second tubular point member 23 of synthdtia ro$in, ~ synthetic resin annular gasket 24 having a rectangular arose aeotion and interposed beteve~an abutting portion$ of the two point members 22, 23, an annular male screw member 5 fitted around the second point member 23, and a cap nut 6 fitted around this first jo~.nt membdr 22 and screwed on the male screw member 5.
The joint members 22, 23 are equal in insxds diameter, each have a predetermined inside diameter over the entire 1&ngth, and comprise thick wall portions 22a, 23a closer to the abutting portions, thin wall portions (not shown) remote from the abutting portions and flange portions 22c, 23a formed at the abutting ends of the think wall portions 22a, 23a, respectively.
The first joint member 22 has an annular recessed poxtion 27 rectangular in cross section and foxmsd in a radially intermediats portion of the abutt~.ng end face thereof. The second joint member 23 has an annular recessed portion 28 rectangular in cross section and formed in a radially intermediate portion of the abutting end face thereof. The portion 22d of the abutting snd face of the first joint member 22 which is positioned radially inwardly of the recessed portion 27 is slightly axially projected beyond the portion 22e of the abutting end face positioned radially outwardly of the portion 27.
The portion 23d of the abutting end face of the second joint member 23 which is positioned rndially inwardly of the reoessed portion 28 is also slightly axially projected beyond the portion 23e of the abutting end face positioned radially outwardly of the portion 28. The two recessed portions 27, 28 provide a portion 26 for acGOmmodating the . gasket 24 therein when th$ joint m~nbera 22, 23 are butted against each other ' The male screw member 5 and the cap nut 6 are made of metal. A flange portion 5a in the form of a hexagonal prism is formed on the male screw member 5 at an end thereof opposite to the abutting portion. The cap nut has a top wall 6a in the form of a bored disk and formed at nn .
end thereof opposite to the abutting portion. the male screw member 5 has an inside diameter approximately equal to the outside dieuneter of thick wall $ortion 23a of the second joint member 23. The~top wall 6a of the cap nut 6 has an inside diameter approximntely equal to the outside a3 diameter of thick wall portir~n 22a of the first joint mQmber 22. As the sap nut 6 is tightened on the ma~.e screw member 5, the male scr~aw member 5 pushes the flange portion 23c of the second joint member 23 axially inward, while the cap nut 5 pushes the flange portion 22c of the first joint member 22 axially inward, whereby the twc~
,joint members 22, 2$ are brought into intimate ~avntact with each other with the ga$ket 24 interposed - therebetween.
The recessed portion 27 of the first joint member 22, the recessed $ortion 28 of the second ,~a3nt member 23 and the gasket 24 ayes approximately equal in inside diameter.
The xsceased portion 27 of the first joint member 22, they recessed portion 2$ of the second jo~.at member 23 and the gask$t~24 are also approximately ~qua~l in outside diameter. The sum of the depths of the two recessed . porticn;~ 27, 28 bas~d cn the radially inward portions 22d, 23d of the point members 22, 23 is slightly smaller than the thickness a~ the gasket 24.
FIG. 5 shows the cap nut 6 as manually tightened up on the male screw member 5, In this manually tightened state of the pipe point 21, approximately half of the gasket 24 is fitted in the reoess~ad portion 27 of the first joint member 22, and the ramaining~'appraximate half of the -Z5. gasket 24 in the recessed portion 28 of the second joint member 23. Ths gasket 24 is held in pressing contact with the bottom surface of the recessed portion 27 of the member 22 and the bottom aurfaae of the r~oessed portion 28 of the member 23. A first gap G1 is present between ' th~ portion 22d of the abutting end face of the first joint member 22 which is positioned radially inwardly of the reoessed portion 27 sad the portion 23d of the abutting end faQe of the second joint member 23 which is positioned rndially inwaz~dly of the recessed portion 28.
A second gap G2 greater than the first gap G1 is present between the portion 22e of thQ abutting end face of the first joint m$mb~er 22 which is positioned radially outWaz~dly of the recessed portion 27 and the portion 23e.
of the abutting snd face of the second joint memmbsr 23 wriich is positioned radially outwardly of the rac~ssed pprtion 28. Examples of dimensions of the$e gortiQns are as follows. The portions 22d, 23d of the joint members 22, 23 radiahy inward of the rocessed portions 27, 28 thereof axially project by 0.1 mm beyond the rad~.aliy 20. outward portions 22e, 23e, respectively. The depths of the recessed porti4~ns 27, 28 are 1.15 mm baSe.d on the raapective radially ~.nward portions 22d, 23d. The gasket 24 is 2 mm ~.n thickneaa, the first gap GI is 0.3 mm end the second gap G2 i$ 0.5 mm.' When the pipe jQ~.nt is further tightened from they i state of FIG. 5, the portion 22d of the abutting and face of the first joint member 22 which is positioned radially inwardly of the recassad portion 27 is first brought into intimate contact with the portion 23d of the abutting and 5 face of the second joint member 23 which is positioned radially inwardly of the reoeased portion 28 approximately over the entire opposed faoe~ thereof. In the state of the joint as praQerly tightened up by further tightening, the gasket 2~ is entirely fitted in the ga:ket 10 sooommadating recessed portion 26 formed by the reoessed portion 27 of the first faint member 22 and the recessed portion 28 of the aeaond joint member 23, the gasket 24 is in intimate contact with the inner surface of the recess~d portion 27 of the member 22 approximately over the entire Z5' area thereof, the aurfaoe of the gasket 24 exposed from the recessed portion 27 is in intimate contact with the inner surfac~ of the recessed portion 2$ of the member 23 approximately over the entire aroa ther$of, and the portion 22e of the abutting end face of the first joint 20 member 22 whioh is positioned radially outwardly of the recessed portion 27 is also in intimate oontact With the portion 23e of the abutting and face of the second joint member 23 which i$ positioned radially outwardly of the recessed portion 28 approximately over the entire opposed 25 faces thereof.

FzG. 6 shotas a second embodiment of pipe ,joint aaaording to the third feature of the invention,. With reference to F=G. 6, the pipe joint 31 comprises a first tubular ,joint member 32 of synthetic resin, a $e~cond tubulax ,joint member 33 of synthetic resin, a synthetic resin annular ga$ket 34 having a rectangular cross suction and interposed between abutting portions of the two point members 32, 33, an annular male screw member 5 fitted around the second ,joint member 33, and a asp nut b fitted 10~ around the first ,joint member 32 and screwed on the wale screw member 5.
The ~e~Lnt members 32, 33 era equal. in inside diameter, each have a predetermined inside diameter over the entire length, and comprise thick wail portions 32a, 33a closer to the abutting portions, thin wall portions (not shown) remote from the abutting portions and flange portions 320, 33c formed at the abutting ends of the think wall portions . 32a, 33a, respectively.
The first joint member 32 has an annular recessed portion 37 rectangular in cross section and foz~med in a radially intermediate portion of the abutting end face thaz~eof. Tht~ second ,joint membesr 33 has an annular recessed portion 38 rectangular in arose aeat~.on and formed in a raBially intermediate portion of the abutting end fees thereof. The abutting end face of the first 2a point member 32 has a portion 32d positioned radially inwardly of the recessed portion 37 thereof and flush with the bottom surface of the recessed portion 37, and a portion 32e positioned radially outwardly of the rwcessed 5' portion 37 and axially pro~eoting beyond the bottom surface of the recessed portion 37. The abutting end face of the second point member 33 has a portion 33d positioned radially inwardly of the recessed portion 38 thereof and axially pro~eating beyond the bottom surface of the i0 recessed portion 38, and a portion 33e positianad radially outwardly of the recessed portion 38 and axially recessed from the bottom surface of the recessed portion 3$. The two recessed portion$ 37, 38, the xadiaily outward portion 32e of the first point mamb~r 32 and the radially inward 15 portion 33d of the second point member 33 provide a poxtion 3b for accommodating the gasket 34 therein when the point members 32, 33 are butted against each other.
The male screw member 5 and the cap nut 5 are made of metal. A flange portion 5a in the form of a hexagonal 20 prism is formed on the males sQrew member 5 at an end . thereof oppa$ite to the abutting portion. The cap nut has a top wall 5a in the form of a bored disk and formed at an end thereof opposite to the abutting portion. Tha male screw member 5 has an insida'diamater approximately egual 25 to the outside diameter of thick wall portion 33a of the d second point member 33. The top wall 6a of the Gap nut 6 has an inside diameter approximately equal to thQ out~s~.da d~temater of thick wall port~.on 32a of the first 3a~,nt member 32. As the cap nut 6 is tightened o~n the male screw member 5, the male screw member 5 pusha~~s the flange portion 33a of the second point member 33 axially inward, while the oap nut 6 pu8hes the flanges portion 32~G of the first ,joint m~mber 32 axially inward, whereby the two point members 32, 33 ar~ brought into intimate contact l0 with each other with the gasket 34 interposed therebe~twaen.
The raaessad portion 37 of the first ,joint member 32, the recessed portion 38 of thm se~oond ,joint mrmber 33 and the gaskwt 34 are approximately equal in inside diameter.
1.5 the re~csssed portion 37 of the fira~t joint member 32, the raoes~sed portion 38 of the seaor~d point member 33 and the gasket 34 are also approximately equal in outside d~.ameter. The depth of th~ recessed portion 37 of the first point member 32 ~.s slightly larger than the 20 thickness of the gasket 34, and the depth of the recessed portion 3$ of the seGOnd point members 33 i: slightly smaller than the thickness of the gasket 34.
F1G. 6 shows the cap nut 6 as manua~.ly tightened up an . the male screw member 5. xn'this manuallx tightened state 25 Of the pips 3oint 31, the gasket 34 is~ sntiroly fitted in ths~ gasket accommodating portion 36, and held in pressing contact with the bottom surface of the recessed paz~tion '~7 ' of the member 32 and the bottom surface of the recessed portion 38 of the. member 33. A first gap G1 is present between the portion 32d of the shutting end face of the first point member 32 which is positioned radially 3.nwardly of the recessed portion 37 and the portion 33d of the abutting end face of the second point member 33 which is positioned re~dially inward~.y of the recessed portion 38. A Second g~xp ~2 greater than the first Qap 01 is present b~trNeen the portion 32e of the abutting end face of the first point member 32 which is positioned radially outwardly of th~ reasesed portion 37 and the portion 33e of tho abutting end faQe of the second point member 33 wh~lch is positioned radie~.ly outwardly of the recessed portion 39. Examples of dimensions of these portions a.~ee as follows. The radially outward portions 32e of the first~~oint member 32 projects b~yond the bottom surface of the recessed portion 37 by 1.5 mm, the radi~.~,ly inward portioxre 33d of thm second ~ o~.nt member 33 prod acts beyond the bottom surface of the recessed portion 38 by 4.7 mm, the radially outward portion 33e of the second ,joint member 33 is recessed from the bottom surface, of the recessed portion 3$ by 1 mm,~'the gasket 34 is 3 mm in thickness, the first gap a1 is 0_3 mm and the. second g~rp G2 is 0.5 mm.
When the pipe point is further tightened from the state of Fzc3. ~, the radially ~.nward portion 32d of the first ,point member abetting end fnce i$ first brought into intimate avntact with the radially inward portion 33d of ' the second faint member abetting end faces approximately over the entire opposed faces thereof. In the state of the pipe joint 31 as properly tightened up by further tightening, the gasket 34 is entirely Pitted in the gawk~t aocommodating re~ce~ssed portion .36 by the recessed portions 37, 38, thrs radially outward portion 32e of the fir$t ,joint member 32 and the radially inward portion 33d of the second joint member 33, with the outer surfaces of they gesk~t 34 in intimate contact with the inner surface of th& accommodating recessed portion 36 approximate~.y over the entire area theroof, and the radially outward portion 32e of the first joint member abetting end ~Eaes is also in intimate contact with the radially outward portion 33e of the second point member abetting end faces approximately over the entire oppa9ed faces thereof.
FIG. 7 shows a third e~mbodimerrt of pipe j vint according to the third feature of the invention. With z~eferenoa to FIC3. 7, they pipe point 41 comprises a first tubular point member 42 of synthetic resin, a saoond tubular ,joint member 43 of synthgtio re~cin, a aynthetio resin annular gasket 44 having a rectangular cross section and interposed between abetting portions of the two joint members 42, 43, an annular male screw member 5 fitted around the seovnd joint member 43, and a cap nut 6 fitted around the first joint member 42 and screwed an the male screw member 5, The point members 42, 43 are equal in inside diameter, each have a predet~rmined inside diameter over the entire - lEngth, and comprise thick wall portions 42a, 43a closer to the abetting portions, thin wall portions (not shown) rote from the abetting portions and flange portions 420, 43a formed at the abetting ands of the thick wall portions 32a, 33a, respectively.
The first joint member 42 has an annular recessed portion 47 rectangular in cross section end formed in a radially intermediate portion of th~ abetting end face thereof. The second joint member 43 also hag an annular recessed portion 48 r~ctangular in cros$ Section and formed in a radiahy intermediate portion of the abetting end face thereof. The abetting end face of the first joint mmmber 42 has a portion 42d positioned radially inwardly of the recessed portion 47 thereof arid further racegsed from the bottom surface of the recessed portion 47, and a portion 42e positidned radially outwardly of the 25- recessed portion 47 and axially projecting beyond tho bottom surfave of the recessed portion 47. The shutting.
and faoe of the ssaand point member 43 has a pardon 43d pasytioned radially inwardly of the recesssd portion 48 ' thereof and axially prp~eoting beyond the bottom surface of the recessed portion 4B, and a portion 43e positioned radially outwardly of the reaassad portion 48 and axially rscassed from the bottom surface of the recessed portfon 48. The two recessed portions 47, 48, the radially outward portion 42e of the first point momber 42 and the radially inward portion 43d of the seavnd point member 43 provide a portion 46 for aavommodating the gasket 44 therein when the point members 42, 43 are butted against each other.
Tha male saraw member 5 and the oap nut 6 are made of metal. ~ flange portion 5a in the form of a hexagonal prism is formal on the male screw member 5 at an end thereof opposite to the shutting portion, The cap nut has a tap wall 6a in the farm of a bored disk end formed at an end thereof opposite to the shutting partioa. The male 20~ sCxaw member 5 has an inside diameter approximately equal to the Qutside diameter of thick wall portion 43a of the second point member 43. The tap wall 6a of the cap nut 6 has $n inside diameter approximately equal to the aut9ida diameter of thick wall portion 42a of the first point member 42. As the oap nut 6 i$ tightened on the male screw momb~r 5, the male, screw member 5 pushes the flange portion 430 of the second point memmber 43 axially inward, whale the cap nut !5 gush~s the flange portion 42c of the first joint member 42 axially inward, whereby the two joint mamb~rs 42, 43 are brought into intimate contact with each other with the gasket 44 intex~poaed th~rebestwenn .
The recessed portion 4? of the first joint me~mbar 42, the recessed portion 4A of the seoond joint member 43 and the gs~sket 44 are approximately ~qua~. in inside diameter_ The recessed portion 47 of the first jo~.nt member 42, the recessed portion 48 of the second j o3.nt membs~r .43 and the gasket 44 are also approximately equal in outside diameter. Ths depth of tlne reo~sssad portion 4? of th~
15' first joint meunbmr 42 is slightly larger than the thiCkne,ss of the gasket 44, and the depth of the recessed portion 48 of the second joint members 43 i~ also slightly larger than the th~.ckness of the gasket 44.
FIG, 7 shows the cap rout 6 as manually tightened up on the male screw member 5. Ire this manually tightdned state of the pipe joint 4.1, the gasket 44 is entirely fitted in the gasket accommodatirig portion 46, end held in pxeesing contaot With the bottom surface of the recessed portion 4?
of the rne~mber 42 and th~ bottom suz~face of the recessed portion 48 of the m$mber 43. A fiz~st gabs Gl is present between the portion 42d of the abutting end face of the first joint member 32 which is positioned radislly inwardly of th~ recessed portion 47 end the portion 43d of the abutting end face of the second joint member 33 which S is positioned radiaily inwardly of the recessed portion 48. A second gap G2 greater than the first gap G1 ie present between the portion 42e of the abutting end face of the first joint member 42 which is positioned radially outwardly of the recessed portion 47 and the portion 43e 10~ of the abutting end face of the second joint member 43 Which is positioned radially outwardly of the recessed portion 48. 8xamples of dimensions of these portions are as follows. The radially outward portions 42e of the fir$t joint meanber 42 projects beyond the bottom surfac~
Z5 of the recessed portion 47 by i_5 mm, the radially inward portions 42d of the first joint member 42 is reaess~d from the bottom surface of the recessed portion 47 by 0.8 mm, ' the rad3allx inward portion 43d of th~ second joint member 43 projects beyond the bottom surface of the reo~ssed 20 portion 48 by 1.5 mm, the radially outward portion 43e of the second joint member 43 is recessed from the bottom surface of the recessed portion 48 by, i_0 mm, the gasket 44 i$ 1 mm in thivkness, the first gap G1 is 0.3 mm and the second gap G2 is 0.5 mm.' 25 When the pipe joint is further tightened from the state of FIG. 7, the. ra83clly inward portion 42d of the first joint msamber abetting end face is first brought into int~.matc. contact with the rad3.ally inward portion 43d of the ~csaond ,point momber abetting and faoe approximately 5~ over the entire opposed faxes thereof. =n the state of the pipe joint 41 as properly tiphtcned up by further tightening, the ggmket 44 ~.c s~ntirely fitted in the ga,skct saQOmmodating recessed portipn 46 by the recessed portions 47, 48, the radially outward portion 42e of the first 10 joint mfr 42 and the radially inward portion 43d of the second joint mcmbez~ 43, with the voter surfcce of the gasket 44 in intimate oontact with the annex surface of the accommodating reoesscd portion 4b appx~oximat~esly over the entire area thereof, and the radially outward portion 15 42e of the first ,joint member abetting end teas is also in intimate contact with the radie~lly outward portion 43e of the second point member abetting end faa~ approximately over the entire opposed faces thereof_ FIG. H shows mother embodiment of pipe joint 2Q aaoording to the first feature of the invention. With reference to FIG. 8, the pipe joint 57. comprises a first tubular ,joint member 52 of synthe~Gic resin, a sevond tubular joint member 53 of synthctio rw~sin, a synthetic resir~ annular gasket 54 having a rectangular cross Section 25 and intezgosed between abetting portions of the two point membaz~s 52, 53, an annular male screw member 55 fitted around the second joint member 53, and a cap nut 56 fitted around the first joint member 52 and screwed on the male screw member 55.
The joint members 52, 53 are equal in inside diameter, Qach have a predetermined insides diameter ovex the entiz~s length, and comprise thick wall portiox» 52a, 53a closer to the abutting portions, thin wail portions 52b, 53b remote from the abutting portion$ arid flange poz~tions 52c, 5~c formed at the abetting ends of tho think wall portions 52a, 53a, respectively.
The first joint member 52 has an annular recessed portion 57 rectangular in cross section and foxms~d in a rndially intermediate portion of the abetting end fnoe thaxsof. The c~aond joint member 53 has an annular ridge 58 rectangular in cro~~, ssation and formed on a radially int$rmediate portion of the e~butting end face thereof.
The male ~~sz~e~w member 55 and the cap nut 56 are made of metal. A f3.an~e portion 55a in the form of a hese$onal prism is formed on the mx~le sorew member 55 at an end thereof opposite to the abetting poxtion. The cap nut 56 has a top wall 56a in the form of a bored disk and formed at an errd thereof opposite to the abetting portion. The male screw member 55 has an inside diameter appro~cimstely 2a equal to the outside diameter of thick wall portion 53a of r the second ~o3nt member 53. The top wall 56a of the cap nut 56 has an inside diameter approximately equal to the outside diem~ter of thick wall portion 52a of the first point member 52.
According to the present embodiment, the outside diameter of the male screw member 55 and the inside di~uneter of the cap nut 56 are greater than the outside diameter of the flange portions 520, 53c of the point m~mber~ 52, 53, and a cl0aranca is formed inside the cap nut 56 around the flange portions 52c, 530 of the point members 52, 53. An annular spaoe~ 59 is dispo$ed in this clearance. Provided between the top wall of the oap nut 58, and thB flake portion 52c of the fir$t point m~mber 52 and the spacer 59 are an annular disk spring 50 and a spring wash~r b0 serving as members for biasing the ~vint member flange portion 52c toward the second point member 53, with the spring wa$her b0 positioned closer to the flange portion 52c and the spacer 59. The spacer 59 has an axial length slightly smaller than th~ sum of the axial lengths of the flange portions 52c, 53c of the two point members 52, 53.
Wh~n the cap nut 56 is tightened on the male screw member 55, the malo screw member 55 pushes the flange portion 53c of the second ~o~nt member 53 axially inward, while the cap nut 56 pushes the flange portion 52c of the first point member 52 axially inward through the disk spring 50 and the washer 60, whereby th~ two point members 52, 53 are brought into intimate Gontaat With each other with the gasket 54 int~rposed thereb~tween.
the recessed portion 57 of the fir~t ~o3nt member 52, the ridge 58 of the second point member 53 and the gasket 54 are approximately equal in inside diameter. The recessed portion 57 of the first point member 52, the ridge 58 of the second point member 53 and the gasket 54 era also approximately equal in outside diameter. The depth of the recessed portion 57 is greater than the amount of prn~ection of the ridge 58, and the thickness of tho gasket 54 is smaller than thB depth of the reaeaaod portion 57. The depth Qf the reoessed portion 57 is slightly smaller than the sum of the amount of prQ~ection~
of tho ridge 58 and the thickness of the gasket 54.
F=Q. 8 shows th~ cap nut 56 as manually tightened up on the male screw member 55. The pip$ point 51 has the same construction as the embodiment shown in FrGB. 1 and 2 except for the spacer 59 arrd the biasing members 50, 60, so that a detailed deaGription will not be given. When the pipe ~Qint Sl is in the manually tightened state, the gasket 54 is entirely fitted in ths.reae~sed portion 57 of th$ first point member 5Z, and pressed against the bottom surfaoe of the reoessgd portion 57 by the ridge 58 of the second point member 53. A fixst gap Gl is present between the portion of the abetting and face of the first point member 52 whfah is positioned radially inwardly of the reaeese8 portion 57 and the portion of the abetting end face of the second joint member 53 which is positioned radiaily inwardly of the ridge 58. A second gap G2 greater than the first gap G1 ie present between the portion of the abetting and face of the first joint member 52 which is position~d radially outwardly of the race$sed portion 57 and the portion of the abetting end fac~ of the s~oond joint member 53 which is positioned radially outwardly of the ridge 58, When the pipe joint 51 is properly tightened up, the g$aket 54 and the ridge 58 of the second point member 53 are entirely fitted in the recessed portion S7 of th~ first point member 52, the outer surface of the ridge 58 of the member 53 is pxessed against the inner surface of the recess~d portion 5~ of the member 52 With the gasket 54 interposed between these surfaces is intimate contact therewith approximately over the entire surfaeo areas, the portion of the abetting end face of the first joint member 52 which is positioned radially inWaxdly of the re~saed portion 57 ie in intimate aantaet with the portion of the abetting end face of the second joint member 5~ which is positioned radially 25~ inwardly of the ridge 58 approximately over the entire opposed faces thereof, and the portion of the abutting end f~:oe of the first ,joint member 52 which is positioned radielly outwardly of the recessed portion 57 is inn intimate contact with the portion of the abutting end face of the second point member 53 which is positioned re~dially outwardly of the ridge 58 agproximately over the entire opposed fac~ss thereof.
Even if th~ synthetic resin point members 52, 53 and gasket 54 undergo alterations with time, the first point member 52 is always biased toward the second ~r~int member 53 by the disk spring 50. This enables the pipe~,joint 51 of the present embodiment to maintain the specific pressure which r~rAatly in~luenass the psrformance thereof in preventing fluid leak.
FiG. 9 shows another ~mbodim~nt of pipe ,joint according to the first ferature of the invention. With reference to FIG. 9, the pi.p~ joint 61 comprises a first tubular joint mevmb~r f2 of synthetic resin, a second tubular point member 53 of sy~nthetio resin, a synthetic 20. resin annular gasket 64 having a rectangular cross section and ~.nterposed between abuttinQ portions of the two ,joint members 62, 63, an annular male screw member 55 fitted around the second point member 63, and a cap nut 56 fatted around the first point member 62 and screwed on the male sorew member 55.

The joint members 62, 63 are equal 3.n inaidv~ diameter, each have a predetermined inside diameter over the entire length, and comprise thick wall portions 62a, 63a closer to th~ abutting portions, thin wall portion8 62b, 63b remote from the abutting port~.ans~ and flange portions 62c, 63c formed nt the abutt~.ng ends of the thick wall portions 62a, 63a., respectively.
The first joint member b2 has en annular recessed portion 67 reotangular in oros~s ssatian and formed in a rndially intermediate portion of they abutting end face thereof. The second jo:tnt member 63 has ran annular rxdgs 58 rectangu~.~sr in cross section and formed on a radisily intermQd3.ate portion of the abutting end face thereof.
The mele sorew member 55 and the Gep nut 56 axe made 15~ of metal. A flange part:Con 55a in the form of a hs~cagonal prism is formed on the male Screw mernbe~r 55 at an end thereof opposite to the abutting portion. The, cap nut 5fi has a top wall 56a in the farm of a bored disk and formed at an end thoreof opposite to the abutting portion. The males screw member 55 has an inside diameter npproximr~tely equal to the outside diameter of thick wall poz~tion 63a of the second ,point member 63. The top wall 56a of the oap nut 5b has an inside diameter approximdt~ly equal to the outside diameter of thick we~7. portion b2a of the first point member 62.

According to the present embodiment, the outsides diameter of the male screw memb~r 55 and the inside di~s,mete~x of the cap nut 56 arcs greater thar~ the outside diameter of the flange portions 62c, 63c of the joint member$ 62, 63, and a clearance is formed inside the cap nut 56 around the flange portions 62a, 63c of the joint members 62, 63. ~ annular spacer 69~is disposed in this cieaxar~ca . provided batweer~ the top wall of the sap nut 56, and the flange portion 62c of the first joint member 10. 62 and the spacer 69 are an annular disk spring 70 and a spring was~har 71 serving as members for biasing the joint member flange portion 62c toward the second ,joint member 63, with the spring washwr 71 positioned a7.osar to the flange portion 62o and the, spacer 69. Al$o provided between the male screw member 55, and the flange portion 63c of the second point member 63 and the apaosr 69 are an.
annular disk spz~~.ng 72 arrd a spring washer 73 serving as members for biasing the joint member flange portion 63c toward th$ first joint memb~r 62, with the spring washer 2p 73 positioned aloaez~ to the flange portion 63G and the spacer 59. The spacer 69 has an e~ial length slightly smaller than the sum of the axial lengths of the flange poz~tions 620, 63c of the two joint members 62, 63.

4~hen the cap nut 56 is tightesned on the male screw member 55, the male screw member 55 pushes the flange portion 63c of the seoond joint member 63 axially inward through the di~k spring 72 and the spring washer 73, while the cap nut 56 pushes thw flange portion 62c of the first joint member 62 axially inward through the disk spring 70 and the spring washer 71, whereby the two joint members b2, 63 are brought into intimate contact with each ether with the gasket 64 interpo:ad therebetween.
ThQ recessed portion 67 of the first joint member 52, the ridge 68 of the second joint member b3 and th$ gasket 64 are approximately equal in inside diameter. The rsces$ed portion 67 of the first joint member 62, the ridge 68 of the second joint member fi3 and the gasket 64 are also approximately equal in outside diameter. The depth of the recessed portion 67 is greater than the iS amount of projection of the ridge 48, and the thickness of the gasket 64 is smaller than the depth of the recessed portion 67. The depth of the recessed portion 67 is slightly smaller than th~ sum of the amount of projection of the ridge 68 arid th~ thiokne$s of the gasket 64.
FzG. 9 shows the cap nut 56 as manually tightened up . on the male screw member 55. The pipe joint 61 has the same conatruotion as the embodiment shown in Fz~S. Z and 2 except for the spacer 6~ and the biasing members 70, 71, 72, 73 so that a detailed description will not be gi~en_ When the pips joint 61 is in the manuallx tightened state, i t the gasket 64 is entirely fitted in the recessed portion 67 of the first point member 62, and prossed against the bottom surface of the reoe$sed portion b7 by the ridge 68 of the second point member 63. A fir$t gap G1 is present between the portion of the abutting end face of the first joint member 62 which is positioned radially inwardly of the recessed portion b7 and the portion of the abutting end face of the second point member 63 which is positioned rsdially inwardly of the ridge 6B. A second gap G2 greatex than the first gap al is present between the portion of the abetting end face of the first joint member 62 which is po9ltioned radially outwardly of the recessed portion 67 and thB portion of the abetting end face of the second joint member 63 which is positioned radially outwardly of the ridge 68. When the pipe point 61 is properly tightened up, the gasket 64 and the ridge 6B of the second joint member 53 are entirely fitted in the recessed portion 67 of the first joint member 62, the outer surface of the ridge fig of the member 63 is pressed against the inner surface of the recessed portion 67 of the member 62 with th$ gasket 64 interposed therebetmeen in intimate contact therewith approximately over the entire areas thereof, the radially inward portion of the . first joint member (62) abetting end fac~ is in intimate contact with the radially inward portion of the second 4~
joint member (63) abetting and face approximately aver the entire appased faces thereof, and the radielly outward portion of the first joint member (62) abetting end face is also in intimate contact with the radially outward portion of tho second joint member ('63) abetting end face approximately over the antir~ opposed faces thereof.
Evan if the synthetic re:in joint members 62, 63 and gasket 64 undergo alterations With tame, the first joint m~mber 62 i9 always biased toward the second joint member 63 by the disk spring 7Q, and the second joint member 63 is biased toward the first joint member fit by the disk spring 72 at all times. This enables the pipe faint 61 of the present embodiment tQ maintain the specific pressure which greatly influences the performance thereof in preventing fluid leaks.
Although the pipe joints shown in FIGS. B and 9 have been described as other embodiments of th~ first feafiure of the invention, the aanstructians of the$e embodiments which are different from the oonstruction shown in FzGS. 1 and 2 oan bs used for the pipe joints embodying the second and third features of the invention. The spacer S9 or 69 can be dispensed with. A disk spring can be added, for example, to the embodiment shown in FIG. 1. The disk spring 50, or disk springs 7b and ~2 can be given an increased diameter by the use of the spacer S9 or 69.

Coii springs can of course b~ used as biasing members in plane of the disk springs 50, 70, 72 and spring washers 60, ~1, 73.
FZG. 10 shows another embodiment of pipe joint according to the first feature of th~ invention. With reference to FIG. 10,,the pipe faint 1 comprises a first tubular joint member 2 of synthetic resin,'a sgoond tubular joint member 3 of synthetic resin, a synthetic resin annular gasket 4 having a rectangular cross section and interpo$ed between shutting portions of the two joint members 2, 3, an annular male screw member 5 fitted around the second joint member 3, a cap nut 6 fitted around the first joint member 2 and screwed on the male screw member 5 and n synthetio resin thrust ring 9 disposed between the inner surfsCe of top wail 6a of the cap nut 6 and the flanges portion 20 of the first point member 2.
This embodiment differs from the first embodiment solely in that the thrust ring 9 is provided in the former. Thus, throughout F=aS. l, 2 and 10, like parts are designated by like reference numerals and will nQt ba de$oribed repeatedly. Incidentally, F=G. 10 is a view corresponds to F=G. 2(a) and shows the cap nut 5 as manually tightdned up on the male screw member 5.
The thrust ring 9 is made from the same material as tho gasket 4 or a matwrial having a smaller coefficient of sliding friction then the material, and is equal to or smaller than the gasket 4 in thiCkness_ For example, the thrust ring has about one-half the thickness of the gasket 4. They thrust ring 9 has en inside diameter approximately e$ual to the inside diameter of the top wall 6a of the cap nut 6, and an autside~ diameter approx~.matsly equal to the outside diameter of the flange portion 2c of the first point memb~r 2. Although annular, the thrust ring 9 ne~ad not always be annular but may be C-shaped.
lb As the cep nut 6 of the pipe joint 1 of the pz~e~asnt embodiment 18 tightened by rotating, the thrust ring 9 slides in contact with the inner surface of the nut top ~oall 6a and the side face of the flange portion 2c of the first joint member 2 relative thereto, preventir~g the first joint member 2 Pram rotating with the cap nut 6.
The same thrust zing 9 as above can be interposed between the forward end face of the male screw member 5 and the second ,joint member 3.
F=G_ 11. shows another embodiment of the pipe joint shown in F=G. ip. This p~,p~a joint 1 comprises a first tubular joint nnember 2 of synthetic resin, a second tubular ,joint member 3 of synthetic resin, a synthetic resin annular gasket ~ having a rectangular cross section and interposed between abutt~ng portions of the two joint 25. m~mbers 2, 3, an annular male screw member 5 fitted around s the second point memb~ar 3, a sag nut 6 fitted around the first faint member 2 and scrawgd on the male screw member and a synthetic resin thrustlring 10 disposed between the inner surface of tap wall 6a of the sap nut b and the 5 flange portion 20 of thQ first ,joint member 2.
This embodiment differs from the first embodiment solely in that the thrust ring 10 is pz~ovided in the former and that the cap nut 6 thereof xs further machined.
Like parts are designated by like raferenae numeral$ and will not be described repeatedly. Incidentally, FIG. 11 is a view aorresponda to FIG. 2(a) and shows the cap nut 6 as manually tightened up an the male screw member 5.
The thrust ring 10 is made from the same material as the gasket 4 or n material having n smaller coefficient of sliding friction than the material, and is equal to or smaller than the gasket 4 in thickness. For example, the thrust ring has about one-half the thickness of the gaska~t 4. The thrust ring 10 hay an inside diameter approximately equal to the inside diameter of the top wall 6a of the cap nut 6, and an outside d~.ameter greater than the outside diameter of the flame portion 2c of the f~.r~st ,joint member 2. Although annular, the thrust ring 10 need not ~xlways be perfectly annular but may be C--shaped.
since the thrust ring i0'is greater than the flange poxtion 2c of the first ,joint membex- 2 in outs:Cde diameter, the cap nut 6 has formed in its inner periphery an annular reoess 6b extending along the inner surface of th~ tap wall 6a for aQCOmmodatir~g th~ outer peripheral edge of the thru$t r~.ng 7Ø Tha annular r~c~ess 6b has an outside diameter approximately equal to the outside diameter of the thrust zing 10. Tha thrust ring Z0, which is made of synthetic resin, has some elasticity, and the outer peripheral edge of the ring can be made to extend along the inner surfacs~ o~ the nut top wall 6a arid fitted into the xacass 6b. This obviates the likelihood that the worker will forget to fit the ring 10 into place, further al~.minating the likelihood of the thrust ring 10 slipping off when the cap nut 6 is removed.
As the cap nut 6 of the pipe ,joint 1 of the pramant embodiment is tightened by rotating, the thrust ring 10 slide~s~ in contact with the inner surf$oa of the nut top wall 6~ x~nd the side face of the flange port~.oz~ 2c of the first point meanbar 2 relative tl~rato, preventing th~
first point member 2 from rotating with the cap nut 6.
The samme thrust ring 9 as shown in F=O. 10 can ba interpasad between the forward and faces of the male screw m~mbar 5 and the second point member 3.
Although the pips ,joints shown 3n FIGS. 9 s~z~d 10 have been described as other ernboc~iment~a of the first faatuxe of the invention, the c~onstructioas of th~ee embodiments which are different from the construsticn shown in FIGB. 1 and 2 can be used for the pipe points embodying the second and third features of the invention.
INDUSTRIAL APPLICAHILITX
The pipe point of the pr~$~nt invention i~ suitable for use with fluids which are highly corrosive to metals and used, far example, in fluid control devisee in a~amiconduotor manufacturing apparatus.
t

Claims

1. A pipe joint comprising a first and a second tubular joint member of synthetic resin, a synthetic resin gasket interposed between abutting portions of the joint members and screw means for joining the joint members, the pipe joint being characterized in that the first joint member is provided in an abutting end face thereof with an annular recessed portion having an opening remaining therein with the gasket entirely fitted therein, the second joint member being provided with an annular ridge on an abutting end face thereof, the ridge being fitted in they opening of the recessed portion with the gasket fitted in the recessed portion, an outer surface of the ridge of the second joint member being pressed against an inner surface of the recessed portion of the first joint member with the gasket interposed between the surfaces in intimate contact therewith approximately over the entire surface areas when the pipe joint is properly tightened up, a portion of the abutting and face of the first joint member positioned radially inwardly of the recessed portion being then in intimate contact with a portion of the abutting end face of the second joint member positioned radially inwardly of the ridge approximately over the entire surface areas thereof, a portion of the abutting end face of the first joint member positioned radially outwardly of the recessed portion being than in intimate contact with a portion of the abutting end face of the second joint member positioned radially outwardly of the ridge approximately over the entire surface areas thereof.

2. A pipe joint comprising a first and a second tubular joint member of synthetic resin, and screw means for joining the joint members, the pipe joint being characterized in that the first joint member is provided with an annular recessed portion in an abutting end face thereof, the second joint member being provided with an annular ridge on an abutting end face thereof, the ridge of the second joint member being fitted in the recessed portion of the first joint member, with an outer surface of the ridge in intimate contact with an inner surface of the recessed portion approximately over the entire surface areas when the pipe joint is properly tightened up, a portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion being then in intimate contact with a portion of the abutting end face of the second joint member positioned radially inwardly of the ridge approximately over the entire surface areas thereof, a portion of the abutting end face of the first joint member positioned radially outwardly of the recessed portion being then in intimate contact with a portion of the abutting end face of the second joint member positioned radially outwardly of the ridge approximately over the entire surface areas thereof.

3. A pipe joint comprising a first and a second tubular joint member of synthetic resin, a synthetic resin gasket interposed between abutting portions of the joint members and screw means for joining the joint members, the pipe joint being characterized in that each of the joint members is provided in an abutting end face thereof with an annular recessed portion for forming a portion for accommodating the gasket therein when the joint members are butted against each other, the gasket being in intimate contact with an inner surface of the recessed portion of the first joint member approximately over the entire area thereof when the pipe joint is properly tightened up, a surface portion of the gasket exposed from the same recessed portion being then in intimate contact with an inner surface of the recessed portion of the second joint member approximately over the entire area thereof, a portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof being then in intimate contact with a portion of the abutting end face of the second joint member positioned radially inwardly of the recessed portion thereof approximately over the entire surface areas thereof, a portion of the abutting end face of the first point member positioned radially outwardly of the recessed portion thereof being then in intimate contact with a portion of the abutting end face of the second point member positioned radially outwardly o~ the recessed portion thereof approximately over the entire surface areas thereof.

4. A pipe joint according to claim 3 which is characterized in that the portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof axially projects beyond the radially outward portion thereof, the portion of the abutting end face of the second joint member radially inward of the recessed portion thereof axially projecting beyond the radially outward portion thereof.

5. A pipe point according to claim 3 which is characterized in that the portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof is flush with the bottom surface of the recessed portion thereof, the radially outward portion of the first joint member axially projecting beyond the bottom surface of the recessed portion thereof, the portion of the abutting end face of the second point member radially inward of the recessed portion thereof axially projecting beyond the bottom surface of the recessed portion thereof, the radially outward portion of the second joint member being axially recessed from the bottom surface of the recessed portion thereof.

6. A pipe point according to claim 3 which is characterized in that the portion of the abutting end face of the first point member positioned radially inwardly of the recessed portion thereof is recessed from the bottom surface of the recessed portion thereof, the radially outward portion of the first point member axially projecting beyond the bottom surface of the recessed portion thereof, the portion of the abutting end face of the second point member radially inward of the recessed portion thereof axially projecting beyond the bottom surface of the recessed portion thereof, the radially outward portion of the second point member being axially recessed from the bottom surface of the recessed portion thereof.

7. A pipe point according to claim 1 or 2 wherein when the pipe point is manually tightened up, a first gap is present between the portion of the abutting end fats of the first point member positioned radially inwardly of the recessed portion and the portion of the abutting end face of the second point member positioned radially inwardly of the ridge, and a second gap greater than the first gap is present between the portion of the abutting and face of the first point member positioned radially outwardly of the recessed portion and the portion of the abutting end face of the second joint member positioned radially outwardly of the ridge.

8. A pipe joint according to any one of claims 3 to 6 wherein when the pipe joint is manually tightened up, a first gap is present between the portion of the abutting end face of the first joint member positioned radially inwardly of the recessed portion thereof and the portion of the abutting end face of the second joint member positioned radially inwardly of the recessed portion thereof, and a second gap greater than the first gap is present between the portion of the abutting end face of the first joint member positioned radially outwardly of the recessed portion thereof and the portion of the abutting end face of the second joint member positioned radially outwardly of the recessed portion thereof.

9. A pipe joint according to any one of claims 1 to 8 wherein each of the joint members is provided at the abutting end face thereof with a flange portion, and the screw means comprises an annular male screw member having a forward and face in bearing contact with the flange portion of one of the joint members, and a cap nut fitted around the other joint member and having a top wall in bearing contact with the flange portion of said other joint member, the cap nut being screwed on the male screw member.

10. A pipe joint according to claim 9 wherein at least one of a space between the male screw member and the flange portion of said one joint member and a space between the top wall of the cap nut and the flange portion of said other flange member has disposed therein s biasing member for biasing one of the joint members toward the other joint member.

11. A pipe joint according to claim 9 wherein an, annular clearance is formed inside the cap nut around the flange portions of the joint members and has an annular spacer disposed therein, and at least one of a space between the cap nut top wall and the spacer and a space between the male screw member and the spacer has provided therein a biasing member for biasing one of the joint members toward the other point member.

12. A pipe joint according to claim 9 wherein a synthetic resin thrust ring is interposed between the cap nut top wall and the flange portion of the joint member.

13. A pipe joint according to claim 12 wherein the thrust ring has an outside diameter larger than the inside diameter of the cap nut, and the cap nut has an annular recess formed in an inner periphery thereof for accommodating an outer peripheral edge of the thrust ring.